Unpublished and grey literature was excluded, as were publications that were not peer-reviewed. Reviews were also excluded if they did not specify the status of the neurodevelopmental disorder examined and did not mention the term “ADHD”. Reviews linking impacts to other neurodevelopmental disorders with common (such as autism, dyspraxia etc.) were excluded. Studies that are not reviews were excluded as well as studies not published in English. Reviews on the prevalence, assessment, interventions, management, treatment and treatment outcomes of ADHD were excluded. Reviews on biological features such as brain correlates, genetics, biological mechanisms, cognitive tests, and executive and motor functions were also excluded. Reviews that did not report a direct link between diagnostic status and risks were excluded. Finally, reviews that reported more than one direct link were excluded as it was not possible to separate the direct impacts and reviews on risk factors for ADHD.

Five databases (PsycINFO, Embase, Scopus, Medline, ERIC) were searched. Following this search and removal of duplicates, a preliminary analysis was conducted of the subject headings (MeSH) and text words (in the title, abstract, and author keywords) related to ADHD and risks. PROSPERO was checked for ongoing or already published systematic reviews on the subject. A full search strategy for Medline (MEDLINE In-Process & Non-Indexed Citations and OVID MEDLINE 1946 to present-Ovid) is detailed in Supplementary Material as an example. The MEDLINE search strategies were adapted for the other databases according to their individual structures. The search was performed in July 2023, date limits were not imposed. While hand-searching was not a strong component of our planned search strategy, the reference lists of all papers that meet the inclusion criteria were hand-searched to check for any additional reviews.

Following the search, all identified citations were uploaded into reference manager software (Zotero). Two of the review authors (BF and GM) independently screened the titles and abstracts for assessment against the search inclusion criteria. Full reports were obtained for all titles that appear to meet the inclusion criteria. The same two review authors screened and assessed the full-text reports in detail against the inclusion criteria. Studies that did not meet the inclusion criteria were excluded and a record of reasons for excluding trials is provided. The study selection process is presented below (Figure 1).

Qualitative and quantitative findings were aggregated into a narrative synthesis. The aggregation/configuration of all themes generates a set of statements that represent the final aggregation (or the development of a theoretical framework, a set of recommendations, or conclusions). Two reviewers (CLH and BF) conducted the syntheses in sequential order; one reviewer developed the synthesis and the second checked the findings. Any disagreement was discussed and/or mediated by a third reviewer.

Following mixed methods review guidelines (67), two review authors (HW and BF) independently critically appraised all selected reviews for methodological quality. 104 of the reviews were systematic reviews (with or without meta-analysis) and were assessed using a standardised quality appraisal tool by the Joanna Briggs Institute Tool for Systematic Reviews (68). The remaining 21 literature or narrative reviews were scored on the Scale for the Assessment of Narrative Review Articles (SANRA, 69) as it was not appropriate to score these on the systematic review checklist. Any disagreement between reviewers was resolved through discussion and/or a third reviewer. The quality rating of each study did not affect the inclusion of the review; all reviews that met the inclusion criteria were submitted to the data extraction and synthesis process.

The study selection process is shown in the flow chart above (Figure 1). Reasons for excluding reviews after full-text assessment are provided in Supplementary Data Sheet 1. In total, 125 reviews published between 1991 and 2023 met the inclusion criteria. The reviews included systematic reviews, meta-analyses, narrative reviews, rapid reviews, and scoping reviews. Characteristics of each review and their review themes are given in Supplementary Table 1 (Supplementary Material 1). A range of countries were represented within the reviews, encompassing a worldwide representation.

Results of study quality are reported in Supplementary Table 1. Following Kmet, Lee and Cook’s guidelines (70), an original quality score from 0 to 1 was calculated for each review. Scores were then classified into poor (0–0.44), moderate (0.45–0.69) and good (0.70–1.00). The same boundaries were used for the scores from the SANRA scale for the non-systematic reviews for consistency in the table. The studies reviewed using SANRA are marked in Supplementary Table 1. Study quality was assessed and agreement between reviewers was 88% overall. The studies showed some variation in their quality. Of the 125 studies, 53 (42%) scored ‘good’, 60 (48%) scored ‘moderate’ and 12 (10%) scored ‘poor’.

Mental health outcomes including addiction, self-harm and suicidality, psychiatric and personality disorders, and poor self-esteem were strongly and consistently associated with ADHD across most reviews included in this synthesis. The reviews we rated as being of ‘good’ quality often included over 50 studies within their analysis, demonstrating the strength of evidence in this area. In the area of addiction, there was consistent evidence that ADHD is associated with addictions to recreational drugs, alcohol and nicotine. For example, the review of Charach et al. (73) reported a significant association between childhood ADHD and alcohol use in adulthood and nicotine in adolescence, although the evidence of an association with drug use was less clear. This review included 49 studies and used appropriate methods of data extraction, synthesis and analysis, providing one of the strongest pieces of evidence in support of an association between ADHD diagnosis in childhood and substance use disorders later in development. Newer areas of research which included fewer reviews showed evidence of associations between ADHD and internet, gaming and gambling addictions, suggesting a relationship between ADHD and addiction which transcends a range of types of addiction. Further research is needed to disentangle the links between ADHD and addiction. For instance, impulsivity, particularly a preference for novelty and sensation-seeking, are core features of ADHD and are also strongly implicated in addictive behaviours (187, 188) making it difficult to clarify which issue comes first in the developmental trajectory. Treatment with methylphenidate is associated with a reduced risk of substance misuse (189) suggesting that reducing ADHD symptoms leads to better outcomes in this area. Arguably, ADHD medications could also reduce addictive behaviours via primary effects on dopamine and norepinephrine (190). Further research is therefore needed to disentangle the complex interactions between ADHD and addiction. Nonetheless, the findings of this review highlight the importance of strategies to mitigate the risk of addictive behaviours in ADHD.

Other aspects of mental health that were associated with ADHD include increased suicidal behaviours and mood disorders, particularly bipolar disorder, in addition to personality disorder. The findings were highly consistent with 8/8 reviews showing a positive association between ADHD and risk of suicide/self-harm, and 8/8 reviews showing increased risk of mental health disorders. Of these, several reviews were rated as poor or moderate quality, undermining the weight of evidence in this area. However, the reviews rated as good quality indicate that these associations are worthy of consideration when developing healthcare strategies for ADHD. In particular, Septier (52) reviewed a large number of studies (59) and used reliable methods for selection and synthesis across studies. They report a significant association between ADHD and suicidal attempts, ideations, plans and completed suicide, highlighting that the ADHD population should potentially be considered as an at-risk group for mental health professionals carrying out risk assessments around self-harm or suicidal intent. Similarly, the review of Allely et al. (29) showed increased rates of self-harm in ADHD.

These findings suggest some commonality in the pathophysiology of these conditions, and this is supported by previous research. One area of potential overlap is emotional dysregulation which is common to ADHD and to mood and personality disorders. Similarly, impulsivity is a core feature of ADHD and may also play a role in completed suicide and self-harm (191). Poor mental health is an important and consistent adverse outcome of ADHD, but it is not always easy to differentiate between ADHD and the clinical profile of these other diagnostic categories. Further research is therefore needed to establish whether these outcomes are latent comorbidities which only emerge at specific life stages, or whether ADHD is a precursor to and risk factor for these adverse outcomes which has implications for treatment and support. For instance, effective treatment of ADHD symptoms may be the best approach to reduce the risk of the onset of an additional mental health disorder, but additional or alternative treatment may be required if this is arising as a comorbidity instead. Furthermore, the poor self-esteem consistently reported in the reviews may be linked closely to mood disorders given that it is often associated with depression.

In summary, adverse mental health outcomes are clearly associated with ADHD and these may require specific intervention to mitigate their onset and improve prognosis. Tailored support is needed for effective treatment of mental health difficulties among people with ADHD as some existing interventions may not be effective given their symptoms and interacting challenges.

Physical health outcomes including sleep, oral health, weight, accidents and injuries, and disease, were also strongly and consistently associated with ADHD across most reviews included in this synthesis. Unlike with mental health, there was a less oblivious relationship between the number of included studies and the overall quality of the review.

Thirteen reviews contributed to our conclusions on sleep, covering over 300 studies. An early review (108) which was rated as poor on our quality assessment suggested significant differences in movement in sleep and sleep apnea, but no differences in sleep-onset or bedtime resistance between ADHD children and controls. However subsequent reviews (109) highlighted parental reports of challenges around bedtime and in the early morning. The limited number of methodologically sound studies in this area was highlighted, which is disappointing as there are objective measures of sleep that can be collected via actigraphy, unlike in mental health where outcomes are nearly always restricted to self or parental report. Greater levels of period limb movement have also been shown to be more prominent in children with ADHD compared to controls (117) although it is not clear how periodic limb movement was differentiated from fidgeting by raters in those studies. Similar results were found for Adults with ADHD, but the bi-directional relationship between poor sleep and ADHD symptoms was much clearer in adult studies. This underlines both the impact of Sleep on ADHD symptom expression, but also how it may create a vicious cycle that maintains both poor sleep and high symptom expression for adults, exacerbating impairments. A high-quality review (113) that explored sleep and ADHD over the lifespan, showed a clear association between lower sleep levels and higher ADHD symptoms. It is tantalising to speculate how improved sleep could reduce Adult ADHD symptom expression (e.g. inattention) and reduce impairment and more support for sleep problems in children and adults with ADHD could provide a credible indirect route for ADHD symptom and impairment reduction.

Six reviews focussed on oral health all were rated good in our quality assessment. Reviews showed that children with ADHD were at a greater risk of dental problems including higher levels of tooth decay and tooth cavities, higher plaque scores and higher dental trauma risks. The mechanisms that might underscore differences in oral hygiene are unclear, but being impatient and impulsive may lead to less time spent brushing, inattention may lead to more frequent skipping of teeth brushing, and the link between ADHD and obesity may also suggest that children with ADHD eat more sugary foods. Previously discussed sleep difficulties in children with ADHD may also play a role in oral hygiene. Bedtime resistance and difficulties establishing and maintaining daily routines may encourage parents to also skip tooth brushing when they finally manage to get their child into bed, and poor sleep quality may explain the higher occurrence of tooth grinding in children with ADHD.

Nine reviews explored the relationship between weight and ADHD although studies were of variable quality. Results consistently demonstrated a significant association between ADHD and obesity, measured in different ways including overall weight and BMI, findings which parents and clinicians may find surprising, given the stereotype of an ADHD child as being full of energy and never sitting still. This association appears to be universal, with Li and colleagues (131) showing especially high levels of obesity in children with ADHD in Europe and Asia. This association between ADHD and obesity can also be mediated by poverty: poverty is often linked with parental ADHD and thus to poorer nutrition. A greater understanding of how to combat obesity in children with ADHD is required, including the potential moderating role of stimulant medication, as well as a greater understanding of how inattention and impulsivity may influence eating patterns.

Eight reviews explored accidents, injuries and ADHD, all of moderate quality. Reviews consistently demonstrated the link between ADHD and a higher risk of accidents, including poisoning, non-intentional injury and bone fractures. The risk of greater accidents was present in both children and adults with ADHD, with a greater risk of traumatic brain injury in adults that was not present in childhood. This risk for adults is most likely associated with the much higher level of car and motorbike accidents experienced by adults with ADHD. Finally, while not always accidental, the link between ADHD and unnatural death is much higher than expected.

Thirteen reviews highlighted the link between ADHD and disease and impairment, studies were all moderate to good in terms of quality. ADHD was associated with a range of diseases or impairing experiences, including asthma, migraine, chronic pain, and sight problems. Evidence for the link between ADHD and celiac disease was inconclusive with different reviews finding evidence for and against an association. While disparate in nature, these findings do highlight the additional burden and impairments for individuals with ADHD over and above the direct burden of the disorder.

There was consistent and strong evidence of associations between ADHD and criminal behaviour, poor educational attainment, and poor relationships, as well as increased levels of risk-taking behaviours including unplanned and teenage pregnancy, and driving-related incidents and offences. These associations were significant for all the reviews included in this umbrella review. Quality of life was also found to be significantly adversely impacted by ADHD in all the reviews included here.

Regarding criminal behaviours, offending and incarceration, there was clear evidence of an association. Mohr-Jensen et al. (163) conducted a large systematic meta-analysis of data gathered from registries held in 6 countries yielding a sample size of over 15,000 children and adolescents who were followed up into adulthood. They reported significantly elevated rates of convictions and imprisonment in ADHD and showed that offending behaviours had an earlier age of onset in ADHD compared with neurotypical peers. They also defined the types of criminal activity to have an impulsive component, indicating a link to one of the diagnostic features of ADHD, which is also linked to emotional dysregulation poor inhibitory control, and alcohol/substance misuse. Similarly, another small but high-quality review (159) reported a significant association between ADHD and intimate partner violence, with some studies identifying alcohol use and comorbid conditions including conduct disorder (CD) and antisocial personality disorder (ASPD) as mediators. It is important to note that one of the reviews (160) found that ADHD is also associated with an increased risk of being a victim of intimate partner and sexual violence. This suggests that the relationships between ADHD and domestic or intimate partner violence are complex and multifactorial, with some of the association explained by additional factors. Some studies included in these reviews suggest that impulsivity may be a core underpinning construct explaining increased criminal activity and violence, and this would also explain the transdiagnostic associations with CD, ASPD, and alcohol use highlighted by Buitelaar et al. (161), which need further exploration. Overall, the evidence of significantly increased prevalence of ADHD in prison settings confirms that this is a notable area of poor outcomes in ADHD and should therefore be a focus of further research and policy development to reduce the likelihood of offending in those with an ADHD diagnosis, particularly when there is comorbidity with CD, ASPD and alcohol use disorder.

Poor educational attainment and occupational outcomes are also significantly associated with ADHD, particularly when ADHD is untreated, and these associations remain significant when variation in intellectual ability is accounted for. Our analysis found worse outcomes from all 5 reviews in this domain which synthesised data from over 200 studies. The outcomes synthesised include leaving school early, achieving lower academic qualifications, unemployment and frequent job changes, and lower pay compared with peers. Christiansen et al. (170) also noted that those with more severe symptoms persisting into adulthood fared worse in employment. The evidence in this domain indicates that poorer academic outcomes are likely to lead to poor employment experiences, highlighting an urgent need to cater for children with ADHD in the classroom to scaffold their learning more effectively, engage them in academic activities more fully, and support them into further studies/employment post-education. Under the Equality Act in the UK (192), ADHD is classified as a disability for which employers must make reasonable adjustments. There is compelling evidence describing the challenges of ADHD symptoms in the workplace (5) but very little research into effective workplace interventions that can support ADHD in the workplace (193). Further research is urgently needed to investigate how best to support children with ADHD in schools, and adults with ADHD in the workplace/higher education institutions. This is particularly important given the increase in adults presenting to services requesting a diagnostic assessment; the ultimate outcome of such an assessment must include recommendations for educators and employers.

Five reviews were included which explored associations between ADHD and relationship difficulties. Between them, these reviews included over 100 studies in this area, designed to assess a range of indicators of social functioning, peer relationships and intimate relationships. All reported evidence of poorer functioning in individuals with ADHD. This manifests as difficulties forming and maintaining peer and intimate relationships, poorer social skills, and differences in social cognition, which may be partially mediated by CD in children (178). Previous research has shown an overlap between ADHD and CD in explaining social cognitive differences in children with ADHD (194). Furthermore, ADHD and autism spectrum disorders frequently co-occur and there is evidence of shared genetic and phenotypic aetiology (195, 196), including difficulties in core social processing skills such as following eye gaze (197, 198). Despite this, none of the reviews included here mentioned autism as a possible mediating factor in explaining relationship difficulties in ADHD, highlighting an area for further research.

Of six reviews focusing on risk-taking behaviours in ADHD, 4 focussed on driving and showed evidence of significantly increased rates of a range of driving outcomes, including accidents, collisions, road rage, and driving citations and offences. The methods of these systematic reviews were judged to be poor quality, largely due to a lack of detail in the methods around core aspects of the search strategy such as the number of databases searched, lack of reliability checks for screening and data extraction, and no quality rating of the included papers. Two of the reviews also overlapped considerably in their included papers and findings. Notably, Vaa (55) highlighted a potential role for CD and ODD in explaining the link between ADHD and driving-related outcomes, suggesting that previous research had overlooked these mediators, and they should be taken into consideration in future research. Another review in this domain focussed on ADHD and pregnancy (182) and reported significant associations between childhood ADHD and CD symptoms and unplanned and teenage pregnancies, with lower academic achievement and substance misuse associated with risky sexual behaviours in girls with ADHD. The authors highlight the lack of research investigating boys with ADHD and predictors of unplanned parenthood at an early age. This area needs further research given the potential impacts on other life outcomes for the individual and the costs to health and social care from unplanned and teenage pregnancies.

Research investigating ADHD has tended to focus on symptom ratings as the primary outcome. Recently, there has been an increased emphasis on other outcomes that may ultimately have greater relevance to those living with ADHD, including quality of life (199). All five reviews included in this umbrella review demonstrated a significant association between ADHD and reduced quality of life, particularly in the areas of school and psychosocial functioning and family and social relationships, with less clear findings related to physical functioning. This may be partly a consequence of the measures used in this field of research which have often been designed for populations with physical rather than mental health difficulties. The reviews also found that parent-rated QoL tended to be lower than children’s ratings where both were gathered. This is a common feature of ADHD, that children (particularly those younger than 12-15 years) may be less able to reflect on or describe their own difficulties and challenges, or they may perceive certain aspects of ADHD symptoms (e.g. impulsiveness) positively, and this has led to a reliance on proxy reports (teachers, parents, school observations) for evaluating children with ADHD. Another interpretation advanced by Danckaerts et al. (173) is that parent ratings of their children’s QoL reflect their burden as parents, and that further work is needed to understand in more depth children’s perspectives on their QoL.

This is the first umbrella review to explore the main impacts associated with having ADHD, including, physical, mental and lifestyle aspects. This review enables findings of reviews relevant to the review question to be compared and contrasted. As such, this review provides a valuable resource for clinicians and academics where these impacts are presented together and demonstrate the wide implications of ADHD. With over 1,000 studies included, this review has the unique advantage of incorporating years of research into one publication. The strengths of this review include the broad focus of the review and the thorough approach to selecting reviews for inclusion. The focus was deliberately broad in order to provide a comprehensive analysis of outcomes associated with ADHD in the core domains that have often been reported as negatively impacted by this condition, including mental health, physical health and lifestyle/social factors. This review enabled us to identify a variability of risks and impacts which can then guide future research studies to explore in greater depth the mechanisms of negative outcomes in ADHD and guide policy development to enhance a range of outcomes for those affected by ADHD.

Despite the strength of this approach, it is important to note that the findings of this review are inevitably limited by the quality of the included reviews and their underpinning studies. Many reviews were rated as poor or moderate, largely because the conduct or reporting of the methodology was unsatisfactory. The quality rating enabled us to determine a high variability in the quality of reviews, however, it is important to bear in mind that these are a reflection of the review methodologies rather than the individual studies and therefore limit our abilities to gauge the quality of each included studies. Our findings are thus constrained by the quantity, quality and comprehensiveness of the available information in the primary reviews. There was large heterogeneity in methodologies and statistical techniques across the reviews, as such, it was not possible to conduct a meta-analysis or directly compare findings between publications. The topics covered by this review are also limited due to the nature of umbrella reviews. While it would be impossible to look at every study investigating this important topic, a review of reviews was the most pragmatic and feasible approach to get a broad understanding. However, topics that have not been synthesised through a review will not have been captured and therefore important factors might be missing. This review was limited to papers published in the English language, resulting in nine studies being excluded. While it is not uncommon to restrict reviews to the English language, these papers might have added important nuances to this review. Finally, while most sub-themes included multiple reviews, a couple only included one. Self-esteem and gender dysphoria were only explored by one review, limiting the evidence for this topic.

Our findings highlight the importance of clinicians taking a holistic approach to the assessment and management of ADHD, being mindful of common co-occurring conditions and impacts on lifestyle. Many people and professionals are impacted by these findings, including healthcare practitioners, social, forensic, education and industries. In relation to mental health conditions, our review highlights the need for clinicians to be mindful in assessing for co-occurring difficulties in addiction, suicide, eating disorders, mood and personality disorders. Our review also indicates that clinicians should be aware of physical conditions such as sleep, oral hygiene, injury and obesity in relation to individuals with ADHD. Future research could explore the development of psychoeducation packages for families and adults to support these areas. These findings could also support the development of future tailored prevention or treatment interventions aimed specifically at ADHD populations, such as tailored exercise or diet management programmes to reduce obesity. Future research could also explore the under-represented areas of gender dysphoria and self-esteem.